7
dc2194af
DEMO MANUAL DC2194A
(Optional) Lower the Default Current Limit Setting for
Channel 1
The default current limit setting for Channel 1 is 7A
peak current limit with VRNG1 tied to INTV
CC
. DC2194A
provides an option to lower the peak current limit setting
for Channel 1 (applications that required lower peak
current limit to effectively protect the power devices during
temporary output overloaded condition or output shorted
circuit) by adjusting the DC voltage level at VRNG1. An
external resistive divider from INTV
CC
can be used to set
the voltage on VRNG pin between 1V to 0.6V, lower the
VRNG1 voltage than 1V resulting in a lower maximum
sense voltage and peak current limit.
(Optional) Operation with Low V
IN
Range
(2.5V ≤ V
IN
≤ 4.5V)
LTM4642 is equipped with CPWR pin, allowing V
IN
to
operate down to V
IN
= 3.3V typical. CPWR pin is the main
input power to the control IC and can be disconnected from
the default V
IN
supply voltage (Remove R13) and tied to
an external 5V bias supply voltage at E14. If the DC bias
supply voltage for CPWR is less than 5.3V, DRV
CC
can
also be tied to this pin by stuffing R15 = 0Ω. Since the
RUN pins of Channel 1 and Channel 2 are directly tied to
V
IN
, pull up resistors at the RUN pins (R9, R23) should
be re-calculated and inserted to make sure the part can
start up at low V
IN
. A good value to start with is 115kΩ
using internal RUN pin pull-down resistor of 100k, RUN
Pin On threshold of 1.1V min. to 1.3V max and RUN pin
absolute max voltage of 6V. Care should be taken by not
exceeding maximum voltage rating on DRV
CC
/INTV
CC
pin
when operating in this mode. Refer to Table 2. for recom-
mended optimized switching frequency while operating at
low V
IN
voltage range.
(Optional) Operation with EXTV
CC
EXTV
CC
pin is available for optional external 5V bias supply
to power INTV
CC
/DRV
CC
. The advantage of using EXTV
CC
is to shut down the internal LDO powered from V
IN
, turn
on the internal EXTV
CC
switch and directly source the ex-
ternal 5V bias supply to power INTV
CC
/DRV
CC
, therefore
improving overall efficiency and reducing temperature
rise of the part, especially at high input voltage range. An
onboard turret (E3) is available for EXTV
CC
with a minimum
of 4.7µF decoupling ceramic capacitor to PGND. Do not
exceed the maximum rated voltage for EXTV
CC
and make
sure V
IN
is powered up before applying EXTV
CC
.
(Optional) Dual Phase Single Output Circuit
Configuration:
DC2194A can be configured as dual phase single output
to provide up to 8A total load current.
The following simple modification is required: (Channel 1
is master, Channel 2 is slave). Please refer to Table 3 for
more details.
Table 3. Dual Phase Single Output Circuit Configuration
PIN NAME CONNECTIONS
MODIFIED COMPONENTS
1
V
OUT1
V
OUT2
Tie V
OUT1
, V
OUT2
together.
Stuff R35 = 0Ω and short the exposed copper pads at V
OUT1
, V
OUT2
on the
bottom layer of the board .
2
FB2
Tie to INTV
CC
to disable the EA of the slave channel.
Remove FB2 bottom divider resistor (R17) and stuff R26 = 0Ω. Note: To
calculate the required bottom feedback resistor divider for the master
channel, use R
TOP_EQUIV
= (60.4k//60.4k) for dual phase single output.
3
COMP2
Left open or externally tied to COMP1.
Remove C11.
4
RUN1
RUN2
Tie RUN1, RUN2 together.
Stuff R25 = 0Ω, R9 = 115kΩ, remove R23.
5
TRSK/SS2 Left open.
Remove JP6.
6
PHASMD Tie to SGND or FLOAT: set phase interleaved 180°
between CH1 and CH2.
JP1 = SNGD or FLOAT.
7
PGOOD2 Left open.
Remove R12.
Quick start proceDure
